Ontogeny of a new Palaeogene pipid frog from southern South America and xenopodinomorph evolution

Lacustrine interbeds of a volcaniclastic succession that crops out extensively in north-western Patagonia yielded impressions of articulated, nearly complete, frogs of different ontogenetic stages including tadpoles. The stratigraphic position of the fossil bearing beds in this sequence and evaluation of palaeofloristic data against the record of climatic change in southern high latitudes support a middle Eocene – early Oligocene age for the frogs. These frogs are described as a new genus and species that resembles the late Palaeocene ' Xenopus' romeri from Brazil, and differs from the middle Eocene S. pascuali from Patagonia, in the relatively wide and short braincase and fused first two presacral vertebrae. However, unlike ' X. '  romeri , the nasals are paired and bear short, but distinct, rostral processes. A parsimony analysis based on 49 adult osteological characters demonstrates that these South American fossil pipids are closely related to xenopodines, restricted to the African continent today, although their interrelationships remain poorly resolved. Interpretation of the ontogenetic stages exemplified by the fossil specimens suggests a developmental pattern more similar to that of extant xenopodines than to the ontogeny of more distant pipoid relatives. Moreover, the similarity between these fossil larvae and those of Xenopus and Silurana strongly suggests similar habits. Many of these larval features may be considered as caenogenetic, i.e. specializations of the tadpoles as obligate, microphagous suspension feeders.  © 2003 The Linnean Society of London, Zoological Journal of the Linnean Society , 2003, 139 , 439-476.     

Determination of Microgram Quantities of Stevioside from Leaves of Stevia rebaudiana Bert. by Two-Dimensional Thin Layer Chromatography

A method is described for the determination of stevioside fromleaves of Stevia rebaudiana Bert. Separation upon non-activatedsilica gel impregnated with boric acid in a two-dimensionalchromatographic system followed by clution and colorimetricassay is reported. Recuperation from chromoplates is over 95%.The observed ratio of the optical density of glucose: steviosidematches that expected theoretically so that glucose may be employedas a standard where pure stevioside is not available. Effects of the plant growth retardant, ancymidol, on the growthand morphology of the shoot system of cucumber (Cucumis sativusL. ) were investigated. Ancymidol inhibited stem elongation,reducing both number and length of internodes. Reduction inleaf area, attributable to a reduction in both cell size andnumber, was accompanied by an increase in chlorophyll per unitarea. The retardant decreased apical dominance and delayed anthesis.Gibberellic acid fully reversed ancymidol-induced inhibitionof stem elongation, internode length and production, and leafexpansion. GA_4/7 and ancymidol gave a synergistic promotionof stem elongation by increasing elongation of younger internodesand increasing internode production. Synergistic promotion ofpetiole elongation by this combination was also observed. Ancymidol,applied 7 d previously either to the shoot or root, severelyreduced the level of gibberellin-like activity in bleeding sapcollected from decapitated plants.     

Bottled Mineral Waters Polluted by Protozoa in Mexico

A survey of protozoa polluting bottled mineral water in Mexico was carried out using samples obtained from the three best-selling brands of bottled mineral water in the country. The organisms were concentrated through filtration procedures and subsequently cultured in sterile media. The cultures were observed over four weeks, with identification to the level of genus and species. Most commonly found were the amoebae Naegleria gruberi, Acanthamoeba astronyxis, and Vahlkampfia vahlkampfi (trophic as well as cystic stages) plus one flagellate, Bodomorpha minima. No ciliates were detected. The public health importance of the findings is obvious, since some strains of Naegleria and Acanthamoeba have the potential to cause human disease that may lead to death.     

A new species of the "mateusi" group: Iberobathynella ortizi sp.n. (Crustacea, Syncarida, Parabathynellidae)

A new species of the genus Iberobathynella Schminke, 1973. is described. The speclmens were found in Cova do Rei Cintolo. Lugo, Spain. The species is included in the "mateusi" group. according to Schminke's (1973) cladistic analysis.     

Conservation and versatility of a new set of primers for long‐PCR amplification of complete insect mitochondrial genomes based on Haematobia irritans mtDNA sequences

The amplification of complete mitochondrial genomes by long PCR (polymerase chain reaction) has been a major contribution to the large‐scale sequencing of arthropodan mitochondrial genomes. In this work, we designed six conserved long‐PCR primers to successfully recover the entire mitochondrial genome of the horn fly Haematobia irritans (Diptera: Muscidae) in two overlapping fragments. The conservation and versatility of these primers were tested for 17 other species from four major insect orders: Diptera (14), Coleoptera (1), Lepidoptera (1) and Hymenoptera (1). The amplification of complete mitochondrial genomes in orders other than Diptera suggested an even broader application of these primers, especially within the Hexapoda.     

Linking plant functional traits with post‐fire sprouting vigour in woody species in central Argentina

Abstract Sprouting vigour is determined by the plant amount of reserves and intrinsic growth rate of plants. While the first factor has been well studied, the second is far less understood. Although a higher growth rate would imply a higher sprouting vigour, fast‐growing species may have less below‐ground reserves, and thus, a lower sprouting potential. The relative importance of both opposite effects was little explored in the literature. To analyse the influence of growth rate on sprouting vigour, one growth season after a fire we measured plant height of the old (pre‐fire) and new (post‐fire) tissue in 194 individuals of 14 woody species from a woodland in central Argentina. We calculated a mean value of pre‐ and post‐fire height for each species, and obtained from a data‐base potential height at maturity, wood density (WD) and specific leaf area (SLA), as surrogates of intrinsic growth rate. We performed a forward stepwise multiple regression using WD and SLA, together with mean pre‐fire height or potential height as independent variables, and mean post‐fire height (as an indicator of resprout vigour) as the dependent variable. Interactions were also tested. Pre‐fire height, WD and their interaction term were the variables that best explained post‐fire height. We also analysed the relationship between pre‐ and post‐fire size for each species independently by fitting hyperbolic functions. Then we correlated both parameters of the functions to species characteristics (WD, SLA, potential height and mean pre‐fire height). Both parameters of the hyperbolic functions were significantly correlated only with WD, but not with the other species characteristics. All results together indicate that species with low WD (i.e. high potential growth rate) regrow more vigorously than species with high WD when pre‐fire individuals were tall. In contrast, when pre‐fire individuals were small, WD had no influence on sprout vigour. A trade‐off between allocation of biomass to underground reserves and shoot growth seems to be responsible for the patterns obtained. For small individuals, below‐ground reserves seem to play a more important role than inherent growth rate (here measured through WD) in determining the sprouting vigour, while for large individuals, growth rate seems more important than reserves.     

Chromosome numbers in Brazilian species of Crotalaria (Leguminosae, Papilionoideae) and their taxonomic significance

Chromosome numbers were counted for 23 species of Crotalaria native to Brazil. Among these data there were new counts for 15 taxa, and some confirmed previous reports or represented numbers that were different from those cited previously. The chromosome numbers most frequently found were 2 n  = 16 and 2 n  = 32. Only C. incana L. had 2 n  = 14 and C. tweediana Benth. had 2 n  = 54. The counts 2 n  = 32 and 54 were found in species of section Calycinae and 2 n  = 16 and 14 in species of section Chrysocalycinae . The data revealed the importance of chromosomal parameters in the characterization of sections Calycinae and Chrysocalycinae in Brazil. We discuss the systematic significance and evolutionary aspects for the genus, comparing the results with the two sections that are native in Brazil.  © 2006 The Linnean Society of London, Botanical Journal of the Linnean Society , 2006, 151 , 271–277.